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Aminoglycosides

3 min read

Aminoglycosides

Key Points

  • Aminoglycosides are potent broad-spectrum bactericidal antibiotics used for severe infections.
  • Many are poorly absorbed orally and are commonly administered IV or IM.
  • They bind the 30S ribosomal subunit and inhibit bacterial protein synthesis.
  • Peak and trough drug levels are essential for safe dose titration.
  • Major toxicities include nephrotoxicity, neurotoxicity, and ototoxicity.
  • Ototoxicity risk increases when combined with loop diuretics.
  • Severe reactions include respiratory paralysis risk after recent anesthesia or muscle relaxants.

Mechanism of Action

Aminoglycosides are bactericidal antibiotics that bind the bacterial 30S ribosomal subunit, inhibit protein synthesis, and lead to bacterial death.

Selected regimens may combine aminoglycosides with beta-lactam antibiotics for a synergistic effect.

Clinical Use

  • Severe gram-negative infections.
  • Serious bloodstream, abdominal, pulmonary, skin, bone, joint, and urinary infections guided by culture results.
  • Streptococcal endocarditis (streptomycin context).
  • Second-line treatment for tuberculosis (streptomycin context).

Nursing Considerations

  • Check allergy history before administration.
  • Obtain cultures before first dose when ordered.
  • Draw blood for peak levels after administration and trough levels immediately before the next dose.
  • Monitor renal function closely: urine output, BUN, creatinine, and GFR trends.
  • Assess for neurotoxicity signs (for example new peripheral numbness or tingling).
  • Assess for auditory changes throughout therapy (tinnitus, hearing changes, vertigo).
  • Monitor WBC trend, fever trend, infection site findings, and culture updates.
  • IM administration should be given in a large muscle when ordered.
  • Use caution with recent anesthesia or concurrent muscle relaxants due to respiratory paralysis risk.

Side Effects and Adverse Effects

  • Common: GI upset, rash.
  • Infectious risk: new diarrhea may indicate C. diff and requires immediate reporting.
  • Nephrotoxicity: increased risk, especially with renal impairment.
  • Neurotoxicity: severe reactions are more likely when renal clearance is reduced.
  • Ototoxicity: risk is increased with concurrent loop diuretic therapy.
  • Reproductive safety: can harm a fetus and breastfed infants.

Health Teaching

  • Report diarrhea, rash, tinnitus, hearing changes, vertigo, numbness, or tingling immediately.
  • Maintain hydration as instructed to reduce nephrotoxicity risk.
  • Understand why scheduled blood-level monitoring (peak/trough) must not be missed.
  • Notify the provider if pregnancy is planned, confirmed, or if breastfeeding.

Self-Check

  1. Why must aminoglycoside trough levels be drawn immediately before the next dose?
  2. Which assessment findings suggest emerging aminoglycoside ototoxicity or nephrotoxicity?
  3. What is the safest nursing response when a scheduled dose is due but trough-level blood draw is still pending?

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